Motor speed and circuit governor



y 2, 1950 s. P. MORSE MOTOR SPEED AND CIRCUIT GOVERNOR 4 Sheets-Sheet 1Filed NOV. 8, 1945 INVENTOR. g i 29mm,

AT/Ofi/VE) M y 50 s. P. MORSE 2,506,312

MOTOR .SPEED AND CIRCUIT GOVERNOR Filed Nov. 8, 1945 4 Sheets-Sheet 2INV EN 73R.

y 1950 s. P. MORSE 2,506,312

\ MOTOR SPEED AND CIRCUIT GOVERNOR Filed Nov. 8, 1945 {Sheets-Sheet I5INVENTOR.

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JTIUIPNEX y 2, 1950 s. P. MORSE 2,506,312

MOTOR SPEED AND cmcuI'r GOVERNOR Filed Nov. 8, 1945 4 Sheets-Sheet 4INVENTOR.

4 7T OR/VE Y a. a Q the c. d di iti cia MGTDR SPEED AND CIREUIT GOVERNORShirley P. Morse, East Haven, fioma, assignor to The A. C. GilbertCompany, New Haven, Conn, a corporation of Maryland Application November3, 1945, Serial No. 621,479

(Cl. 31830l) 16 Claims. i

This invention relates to centrifugally responsive manually settablecircuit controllers for starting, stopping and/or regulating the speedoi. running of an electric motor and relates par-= ticularly to circuitcontrolling mechanisms suited to share with the 'motor the interiorspace of the torpedo-shaped casing of an electrically powered kitchenfood mixer.

It is advantageous in this kind of electrically powered appliance tolocate a manual rotary circuit controller for starting, stopping anddetermining the speed of the motor at the rear end ofv the motor housingopposite that end which carries the motor driven working tool or foodagitator. Since it is desirable also to provide the motor housing with atapering and rounded rear end, peculiar restrictions are imposed uponthe space that is available in such housing for circuit governingmechanism located at the end of the motor shaft.

The present improvements concern construction and disposition of suchelectric circuit gov crning mechanism having as one aim a. moreadvantageous use of the above mentioned available housing space and asanother aim increased simplicity and ruggedness of such mechanismswherever used yielding greater economy in their manufacture andrendering them more dependable in performance as well as permittingeasier servicing, repair and adjustment in the subject type ofappliance.

One object of this invention is to enable a single speed setting rotarycontroller handle to serve to stop and start the motor as well as todetermine the motor speed without complicating the structure of thehandle turned controller with space consuming cam surfaces.

A further object is to provide means for calibrating a motor speedregulator by instrumentalities requiring a minimum of manipulation ordisassemblage of appliance parts for setting the speed indication intotrue conformity with a test performance of the actually maintained motorspeed.

A further object is to save axial space by interposing between the endof the motor shaft and the speed setting controller a novel arrangementof contact carrying flaps that are wavable toward and away from eachother as well as relative to the motor shaft.

A further object is to equip the above mentioned flaps with cooperativecircuit making and breaking contacts in such arrangement that one of theflaps facing the motor shaft may be oscillated broadside in proportionto changes in motor speed by the simplest of centrifugal devices carriedon the motor shaft, while the other contact equipped flap may face thespeed setting controller and be adjusted broadside thereby to differentselected positions for determining what motor speed shall automaticallybe maintained through action of the centrifugal device.

A particular object is to utilize a speed setting handle coupledoperatively like a wrench to the interior electric contact positioningparts which it actuates, thus to be freely separable from such parts.

A further object is to organize the aforementioned electric circuitgoverning mechanism, together with a separable end section of theappliance casing which supports it, into an in tegrated structure whichmay he applied and re moved as a unit from the motor and from theremainder of the appliance casing in which the motor is housed.

A further object is to utilize the aforesaid single speed settingcontroller handle, which also serves to start and stop the motor, toserve also to short circuit the aforesaid flap-carried speed regulatingcontacts and thereby relieve the latter from having to carry the heavycurrent load drawn by the motor when heavily loaded, such as whencoupled to drive food prccessing'accesseries for extracting fruitjuices, grinding meat, cracking ice, seeding raisins, etc.

A further object is to organize all of the electric contact carryingparts into a unitary subassemblage which may be removed as such from theabove mentioned controller structure. a

A still further object is to make use of screw means foreffecting speedcalibrating adjustment and also to make use of the same screw means forfastening axially together interior and exterior sections of a speedsetting manual controller.

These and related objects of the improvements will appear in greaterparticular in. the following description of a successful embodiment ofthe invention which has reference to the appended drawings. In thedrawings arrows applied to section planes indicate the direction inwhich the subject is viewed in those figures or the drawings whosenumbers correspond to the numbers applied to the arrows.

Fig. 1 is a side view of an electrically powered kitchen food mixingappliance in which is incorporated a manually settable motor circuit governing mechanism embodying the present improvements.

Fig. 2 is a view looking from the left in Fig. 1 at the rear end of theappliance showing the m0- tor speed setting handle and speed indicatingindicia.

Fig. 3 is a view drawn on an enlarged scale taken in section through themotor speed governing mechanism on the plane 3-3 in Figs. 2 and 5.

Fig. 4 is a perspective view of the speed setting unit separated fromthe motor section of the appliance.

Fig. 5 shows the rear face of the subassemblage cl circuit making andbreaking contacts removed from the unit of Fig. 4 and viewed from theplane 5-5 in Fig. 3.

Fig. 6 is a view taken in section on the plane 6-8 in Fig. 5.

Fig. '7 shows the switch base plate viewed as in Fig. 5 with thestarting and stopping contacts partially broken away to expose the speedregulating contact carrying flap.

Fig. 8 shows the opposite or front face of the subassemblage of Fig. 5as viewed from the plane 8-8 in Fig. 3.

Fig. 9 is a fragmentary view taken in section on the plane 99 in Fig. 3showing swivel limiting stops for the speed setting handle.

Fig. 10 is a fragmentary view taken in section on the planelll| in Fig.8 showing a positioning detent for the speed setting handle.

Fig. 11 shows the empty interior of the speed setting unit of Fig. 4with its subassemblage of circuit making and breaking contacts of Figs.5, 7 and 8 removed.

Fig. 12 is a perspective view of the front face of the subassemblageshown in Fig. 8 removed from the structure of Fig. 11.

Fig. 13 is a perspective view of the rear face of the same subassemblageshown in Fig. removed from the structure of Fig. 11.

Fig. 14 is a schematic diagram of electric circuits and wiringconnections embodying one form of improved electrical systems madepossible by the structures illustrated in the remaining figures of thedrawings.

The motor circuit governor of these improvements is particularly adaptedfor installation in the rear end of a household food mixing appliancesuch as that shown in Fig. 1 whose motor and external instrumentalitiesare more completely shown in United States Patent No. 2,292,566, grantedAugust 11, 1942. The torpedo shaped casing or housing structure of theappliance is indicated as a whole at l0 and for purposes of the presentinvention is divided into a main, motor surrounding section I l and arounded end section I2. As in Figs. 7, 8 and 9 of the aforesaid patent,the main casing section H may support the spindle or spindles S ofconventional food agitators not shown, as well as a lateral power socketH or a top power socket F into which can be inserted the tenoned shaftof a food processing accessory such as a fruit juicer, meat grinder, icecracker, raisin seeder or the like. This main casing section II alsocontains power transmission and chuck devices that conple the motordrivingly to such spindle, spindles, or accessory shafts as are fullyset forth in the said patent.

In the main housing section a rotor bearing I! for a motor armature andits shaft i6 is lodged in a housing partition wall II, as is also athrust washer l8 for the axial thrust ball bearing 89. There is fastenedon the end of shaft l6 by set screw 22 the hub 23 of a centrifugal speedregulator indicated as a whole by 24. This automatic regulator asindicated in Figs. 3 and 8 may be of conventional construction andcomprises two oppositely bowed spiders 25 and 26 each having four limberresilient radial arms, alike, joined together at their outer ends byfastenings 21 which also secure to said arms the centrifugal weights 28.The spider 25 nearest the motor is fixed on hub 23. The other or outerspider 26 carries coaxially with shaft IS a pressor button 2! whichmoves closer to the end of the shaft as 1 increasing rotary speed of themotor shaft and regulator brings centrifugal forces to play upon theweights 28.

The rounded end section I2 of the appliance housing structure isprovided with a circumferential rabbet 34 which fittinglyengages anannular terminal lip 35 on the main housing section II and is removablyheld in place fixedly by one or more screws such as 36. If desired theappliance handle 20 may also be fastened to section i2 by a bolt 2|.Thus end section l2 together with its entire carried speed governingswitch mechanism is integrated in the form of a unit shown detached fromthe main housing section it and from handle 20 in Fig. 4.

' Referring to Figs. 3, 4 and 11 the rotary, speed setting controller,designated 3'! as a whole, is shown to comprise a handle knob 38 outsidethe end housing section l2 and an actuator 39 inside of this housingsection including a crank post 5! and a wrench-like socket l8. Actuator59 is operably joined to handle 38 by a tie bolt 40 which may containthe socket l8 and whose head flange 4| draws the actuator 39 tightlyagainst a hub 48 portion of handle 38 when nut 42 is tightened. Nut 42is on the threaded end 43 of tie bolt 49 which has a screw driver slot44 and is concealed in a central recess 46 in handle 38 covered by aremovable snap plate 65 which can be forced into and pried out of ashallow counterbore around this recess. Tie bolt til extends with freelysliding clearance through a hole 5! in handle 38.

Hub 48 of handle 38 is thus journaied to turn freely in a centralbearing hole is through the dome shaped wall iii of end section i2 andis retained axially in place by the actuator 39 which is of large enoughcompass to overlap the inside of wall l3. Handle hub 48 is grooveddiametri caliy at 49 and fittingly receives at least one key lug 50fixedly carried by actuator 39 so that the actuator always turns inunison with handle 38. The extent of rotary movement of controller 31 islimited to less than a complete turn by a stationary stop abutment 52projecting from the inner surface of wall l3 which encounters the turnlimiting shoulders 53 and 54 on actuator 39. Crank post 5|, and ifdesired other portions of actuator 39, will preferably be made ofinsulating material.

A group or current conductive parts, including broadside wavable flapscarrying circuit making and breaking terminals or contacts that aremovable jointly by the centrifugal regulator 24 and by the speed settingmanual controller 31, are disposed between and transverse the axis ofsuch regulator and controller. These parts are all carried as a unit ona switch base plate 55 which is preferably of insulating material. Baseplate 55 is removably fastened against an annular shoulder 56 formedinternally on the removable end housing section 12 by'screws 51 whichen- -gage with threaded holes in bosses 58 cast integrally with the wallof this housing section. A rectangular aperture 59 is cut inbase plate55 and is occupied by a marginal portion of a stifi card flap ofinsulating material swingably supported at one of its edges by a narrowthin twistable hinge strip 5! fastened to card 60 by eyelets 82 so thatthe card flap is wavable to and away from flush relation to the baseplate. These eyelets are electrically conductive and also serve to clampagainst the reverse face of card 60 the mounting flange 53 of a limberresilient U-shaped conductive flap 64 carrying at its opposite or freewidened end two speed governing circuit terminal contacts 65 alike inpolarity. Opposed respectively to contacts 65 are two contacts 56 alikein polarity but of different polarity from that of contacts 55. Contacts66 are car- '5 ried by a, rigid conductive bridge strip 81 firmly fixedto card 60 by eyelets 68. The resilient flap 54 is normally so sprung asto tend to separate contacts 65 from contacts 66, but hinge strip IiIserves merely as a current conductor and simple form of pivotalanchorage for the card flap 60,

- exerting preferably little or no bias on the latter in eitherdirection of the latters useful small range of swinging movement.Eyelets 69 fix H According to the present improvements the switch baseplate 55 also carries bearing support for a speed setting adjuster 13,such support being stationed on the end section I2 of the housingstructure independently of and apart from the controller 31. The speedsetting adjuster I3 is thus located between motor shaft I8 and the saidmanual controller in axial alignment with both of them. Specifically inthe form herein illustrated, the bearing support includes a stiffbracket 14 of conductive material in which is fixed in coaxial relationto the motor shaft an internally threaded bushing I5. Bracket I4 isfastened to the switch base plate 65 by eyelets I5. The aforementionedadjuster I3 takes the form of a screw adjustably turnable in threadedengagement with bushing I5 and having a fiat sided head I1 slidablyfitting a fiat sided socket I8 formed in the end of actuator 39. Thusadjuster I3 is operably related to the controller 31 while the latterremains freely separable from the former for permitting all of the partscarried by switch base 55 to be removed from the housing section I2without disturbing the assemblage of controller 31 with this housingsection.

We now come to the motor starting and stopping switch contacts carriedby base plate 55 in position to be actuated by the crank post SI of theactuator 39 of the manual controller 31. These include a spring leafconductor arm 82 having one end fixedly anchored at its base end onbracket I4 by means of eyelets 83 and adapted at its free end to makeand break contact with the overhanging shelf-like end of a stiff bentstrip terminal 84 which is fixedly stationed on the base plate by athrough eyelet 86 and is elongated to extend through a closely fittingslot in the base plate and projects from the opposite face thereof toserve as a connector prong 85.

Another spring leaf conductive arm 81 and another elongated connectorprong 88 are conductively joined and fixed on base plate 55 by a througheyelet 89, prong 88 extending through a closely fitting slot in baseplate 55 and parallel to prong 85. The free end of the spring leaf arm81 overlies and makes and breaks contact with the bracket I4. There is athird connector prong 90 similarly fixed on the base plate by an eyelet9I and extending through a closely fitting plate slot. Eyelet 9I alsoclamps a conductive bus strap 9-2 against the mounted end of prong 90which carries current to the aforementioned hinge strip 6| of the cardflap 60. It has heretofore been mentioned that hinge strip GI is inpermanent electrical connection with the conductive contact carryingflap 64 through eyelets 52.

A flexible lead wire 93 electrically connects the conductive bridgestrip 61 on card flap with eyelet 89 that fastens prong 88 to base plate55 and without appreciably impeding free swinging movement of the cardflap. The lead wire 93 passes from one face of base plate 55 to theother through holes 94 which enable wire 93 to cross the hinge strip 8|at a point where it is mechanically and electrically separatedtherefrom.

Fig. 9 shows a circular series of sunken spots 95 on the inner concaveface of handle skirt 9. whose outer convex face is marked with speedindicating indicia 9I turnable into selective register with the indexarrow 98 carried on the stationary wall I3 of housing section I2. Adetent ball 99 is pressed by spring I00 into the circular path traversedby sunken spots 95 as the knob handle 88 is turned and serves toyieldably retain the handlein any of its several Set rotary speedselecting positions. spring I00 is free to expand axially in a bore IOIin boss I02 formed on the interior of housing section I2. The rear endof bore IOI faces the switch base plate 55 so that the latter retainsthe spring I00 in this bore and serves as removable thrust abutment forthe spring.

In applying and removing the speed governing unit of Fig. 4 from themain body of the appliance, the free ends of the before describedconductive prongs and 88 wipe into or out of conductive engagement withspring clip circuit terminals I55 and I56, respectively, which connectelectrically to the two sides of the motor. The third prong in likemanner wipes into and out of conductive engagement with a third springclip circuit terminal I80 which connects electrically with a condenserI8I arranged in shunt relation to speed regulating contacts 65 and 58for reducing sparking thereat. As indicated in Figs. 3 and 14 each ofthe three spring clip circuit terminals I55, I56 and I80 is mounted onan insulative supporting plate I57 that may be fixed on the partitionwall I! of the main section of the appliance housing. The plates I51 aswell as wall U have registering apertures I58 to admit the prongs 85, 88and 90 as the latter are thrust forward in joining the unit of Fig. 4 tothe main body of the appliance.

With particular reference to Fig. 14, in conjunction with other figuresof the drawings, the operation will be described by starting with thespeed setting handle 38 positioned as in Fig. 2 where the indicium Offregisters with index arrow 98. At this time the shoulder 53 of theactuator 39 is at rest against the stationary stop lug 52 on the housingwhich permits only clockwise turning of the handle from its position inFig. 2. Also in this "Off" position the crank post 5| bears againstspring leaf arm 82 and holds the latters free end separated from bentstrip terminal 84, arm 82 being so sprung as normally to tend to contactwith terminal 84.

While there are many possible circuit arrangements that will causemaking and breaking of contact between 82 and 84 to start and stop themotor, Fig. 14 diagrams an electrical system in which current is fed toan appliance through two wires I90, I9I of a flexible attachment cordI92 shown in Fig. 1. Wire I90 leads to one field winding of the motorwhose opposite end connects to a spring clip I 55. The other wire I9Ileads to the other field winding of the motor and thence through themotor brushes and armature M to the spring clip I58 and also to thecondenser I8I whose other side is connected to spring clip I80. Thus itwill be seen that in the above described starting position of the partsall current from wire I90 is dead-ended at 84.

When handle 38 is turned clockwise in Fig. 2, crank post 5I swings clearof the spring leaf arm 82 permitting the latter to engage conductivelythe bent strip 84 which will complete a circuit through I90m0tor fieldwindingI55.85-

iii-motor field winding-lei. Current can not at this time pass throughprong 90 because circuit i through the latter is dead-ended at condenserill. The motor will now start and speed up until centrifugal forceacting on regulator 28 draws thepresser button 29 toward the right.Followup of card fiap 60 is occasioned by the spring tension in flap 84which always tends to separate speed regulating contacts 65, 68 andfinally is able to do so when the motor has attained the speed for whichthe adjuster 13 has been set by handle 38. Upon this automaticseparation of contacts 65, 66, the above said circuit through the motorwill become broken and as the motor loses upon to drive. As the adjusterI3 is moved toward the right in Figs. 3 and 14 by clockwise turning ofhandle 38 in Fig. 2, a higher and higher speed of the motor will berequired to draw presser button 29 far enough to the right to separatecontact 66 from contact 65 as is well understood in this art.

The present circuit governing mechanism incorporates a new and valuablefeature in the ability to relieve the automatic speed regulatingcontacts i5, 66 of carrying the heavier current drawn by the motor whenit is loaded with relatively heavy duty accessory appliances such asfruit juices, meat choppers, etc. This is accomplished by providing anadditional circuit from the prong ll through the spring leaf conductivearm 81 to the bracket 14. This circuit is made when arm '1 is thrustinto conductive contact with bracket M in the extreme rotary position ofcrank post I occasioned by turning handle 38 clockwise as far as it willgo in Fig. 2. On this occasion limit shoulder 54 on actuator 39 bringsup against the stop 52 and in this position, crank post 5| rides ontothe sloping free end portion of spring arm '1 forcing the latterconductively against bracket 14. This short circuits the regularcontacts 65, 68 so that these contacts are relieved of carrying heavyload currents for lon periods of time. The circuit by which the motor isnow energized becomes, I 90-field windingl 55B58482 l4-8'I-88-l56-motorbrush and armaturemotor field windingl9i. As soon as handle 38 is turnedbackward, or counterclockwise, contact breaks between 14 and 81restoring the automatic control of the motor speed to contacts I and 66.

Many different arrangements of electric circuits incorporating a powermotor, and if desired various electrical units for introducing into suchcircuits fixed or variable electrical capacitance, inductance,resistance or transformer effects, will suggest themselves to thoseskilled in this art, wherefore the appended claims are directed to andintended to cover all variations in electrical system as well as allobvious substitutes for the herein illustrated mechanical parts andarrangements that fairly come within the language of the claims.

Certain combinations of elements and features of the invention disclosedherein are claimed in my copending application divisional herefrom,Serial No. 15,616, filed March 18, 1948.

I claim:

1. In a governor for motor circuits in an elec- 8 trical appliance, thecombination with an appliance housing of, a motor shaft, a centrifugalspeed regulator arranged on said shaft to perform movement axiallythereof responsive to changes in rotary speed, a speed setting controller rotatably supported in an end portion of said housing andturnable coaxially of said shaft comprising a handle outside of saidhousing and an actuator inside of said housing portion operablyconnected to said handle, a speed adjuster operablyrelated to saidactuator located between the same and said motor shaft, bearing supportfor saida'djuster stationed on said housing structurally apart from saidcontroller, and cooperative circuit making and breaking memberselectrically operative to govern the motor speed constructed andarranged to be moved relatively by. said centrifugal regulator and bysaid speed adjuster.

2. In a governor for motor circuits in an electrical appliance, thecombination defined in claim 1, in which the said speed adjuster isjournaled for rotary movement in the said bearing support.

3. In a governor for motor circuits in an electrical appliance, thecombination defined in claim 1, in which the said bearing supportcontains a threaded hole in coaxial alignment with the said motor shaftand the said speed adjuster comprises a screw threaded member rotatablysupported in said threaded hole.

4. In a governor for motor circuits in an electrical appliance, thecombination defined in claim 1, in which the said handle and the saidactuator have axially abutting faces, together with a tie bolt, shapedand arranged to hold said actuator and said handle tightly together,said tie bolt being aligned axially with said shaft and extendingthrough said handle to be accessible outside of the said housingstructure.

5. In a governor for motor circuits in an electrical appliance, thecombination defined in claim 1, in which the said bearing supportcontains a threaded hole, and the said speed adjuster comprises a screwthreaded member rotatably supported in said threaded hole in coaxialalignment with the said motor shaft, and the said actuator is rotatablycoupled to said speed adjuster in a manner permitting free axialseparation of the former from the latter.

6. In a governor for motor circuits in an electrical appliance, thecombination defined in claim 1. in which the said bearing supportcontains a threaded hole, and the said speed adjuster comprises a screwthreaded member rotatably supported in said threaded hole in coaxialalignment with the said motor shaft, said adjuster and said actuatorbeing cooperatively shaped to fit separably together in rotaryinterlocked relation.

7. In a governor for motor circuits in an electrical appliance, thecombination defined in claim 1, in which the said bearing supportcontains a threaded hole, and the said speed adjuster comprises arotatable screw with a flat sided head supported in said threaded holein coaxial alignment with the said motor shaft, the said actuatorhavinga fiat sided socket receptive to said screw head with a rotaryimpelling fit.

8.In a governor for motor circuits in an electrical appliance, thecombination defined in claim 1, in which the said handle and the saidactuator have abutting shoulders, together with a tie bolt holding saidshoulders firmly together, and the said bearing support contains athreaded hole, and the said adjuster comprises a screw rotatably 15supported in said threaded hole, together with means impellably couplingsaid actuator in separable relation to said adjuster'comprising a flatsided head on said screw and a flat sided socket in said actuator.

9. In a governor for motor circuits in an electrical appliance, thecombination defined in claim 1, in which the said handle contains acentral clearance hole, and both the said actuator and said handl havemutually abutting faces, said actuator further having a thrust affordingface overlapping the inside of the said housing structure, together witha tie bolt extending through said clearance hole having a threaded endoutside of the latter, and a retaining nut on said threaded bolt endadapted to clamp said abutting faces firmly together in the presence ofswivel permitting axial clearance between said housing structure andsaid overlapping thrust face of the actuator.

10. In an electrical appliance having a motor enclosed by an appliancehousing, a motor circuit governing electric switch unit comprising incombination, a cupped end section of the appliance housing detachablymountable on the appliance, current switching mechanism located insideof said detachable housing section, a manual controller for operatingsaid mechanism joined in freely separable relation thereto and carriedby said detachable housing section in a manner to be accessible outsidethe latter, and a base carrying said current switching mechanismdetachably mounted in said cupped housing section to be removable inunison with said current switching mechanism therefrom.

11. In an electrical appliance having a motor enclosed by an appliancehousing, a motor governing electric switch unit as defined in claim 10,in which the said current switching mechanism comprises circuit makingand breaking contacts carried on the opposite side of the said base fromthe appliance motor, together with current conductive prongs carried onsaid base and elongated toward the motor of the appliance for makingbreakable circuit connections between the latter and said switchingmechanism.

12. In an electrical appliance having a motor enclosed by an appliancehousing, a motor governing electric switch unit as defined in claim '10,in which the said base comprises an insulative plate containing acentral aperture, and the said current switching mechanism includes acircuit making and breaking contact, together with a flap carrying saidcontact hinged on said base in position to occupy said aperture and toswing into and out of substantially planar alignment with said plate.

13. In an electrical appliance having a motor enclosed by an appliancehousing, a motor governing electric switch unit as defined in claim 10,in which the said base comprises a plate containing an aperture andhaving a planar surface, and the said current switching mechanismcomprises a circuit terminal mounted on said base plate, a contactmovable into and out of conductive engagement with said terminal, astifl. card-like flap having a flat broadside face carrying saidcontact, and a hinge device swingably coupling a marginal portion ofsaid flap to said base plate at one edge of said aperture in suchposition that said marginal flap portion occupies said aperture whilesaid broadside face of the flap is wavable toward and away fromsubstantially coplanar alignment with said planar surface of the baseplate.

14. In an electrical appliance havinga motor in which the said basecomprises a plate, and the said current switching mechanism comprises acircuit terminal, a contact movable into and out of conductiveengagement with said terminal, a stiff card-like flap carrying saidcontact, and a hinge device swingably coupling said flap to said baseplate comprising an elongated straight thin narrow strip of twistablematerial secured to said base plate at opposite ends of the longitudinalaxis of said strip and having an intermediate portion of its lengthparalleling a marginal portion of said flap and secured thereto, wherebysaid strip functions as a hinge device by twisting along its said axis.

15. In an electrical appliance having a motor enclosed by an appliancehousing, a motor governing electric switch unit as defined in claim 10,in which the said base comprises a plate, and the said current switchingmechanism comprises a foldable flap comprising two thin leaf-like armsfacing each other broadside, at least one of said arms being resilientand tensioned toresist relative closing movement of the arms,-cooperative circuit making and breaking contacts carried respectively bysaid arms in position to engage and separate when said arms arerespectively closed and opened, a stationary abutment adjustable by thesaid manual controller to variable positions for limiting openingmovement of one of said arms, and a circuit regulator constructed andarranged to urge th other of said arms in arm closing direction towardsaid stationary abutment against the tension in said resilient arm.

16. In an electrical appliance having a motor enclosed by an appliancehousing, a motor governing electric switch unit as defined in claim 10,in which the said base comprises a plate, and the said current switchingmechanism comprises two contacts movable into and out of conductiveengagement, a stiff card-like flap of insulative material carrying oneof said contacts, a bowed leaf of resilient conductive metal attached tosaid flap and carrying the other of said contacts, a flexible currentconductor trailing said flap carried contact, and a straight thin narrowstrip of twistable conductive material electrically connected to saidresilient leaf having its opposite ends secured to said base plate, anintermediate portion of the length of said strip being secured to saidflap thereby to enable said strip to conduct current to said resilientleaf while swingably coupling said flap to said base.

SHIRLEY P. MORSE.

asrsnsucss orrsn The following references are of record in the file ofthis patent:

' UNITED s'm'ms ra'mn'rs

